| From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 107/273] mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progress | Date | Mon, 7 Mar 2016 14:48:18 -0800 |
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4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
commit 564e81a57f9788b1475127012e0fd44e9049e342 upstream.
Jan Stancek has reported that system occasionally hanging after "oom01" testcase from LTP triggers OOM. Guessing from a result that there is a kworker thread doing memory allocation and the values between "Node 0 Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not up-to-date for some reason.
According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress"), it meant to force the kworker thread to take a short sleep, but it by error used schedule_timeout(1). We missed that schedule_timeout() in state TASK_RUNNING doesn't do anything.
Fix it by using schedule_timeout_uninterruptible(1) which forces the kworker thread to take a short sleep in order to make sure that vmstat is up-to-date.
Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Cc: Cristopher Lameter <clameter@sgi.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Arkadiusz Miskiewicz <arekm@maven.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- mm/backing-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 632b79b..ebab43e 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -975,7 +975,7 @@ long wait_iff_congested(struct zone *zone, int sync, long timeout) * here rather than calling cond_resched(). */ if (current->flags & PF_WQ_WORKER) - schedule_timeout(1); + schedule_timeout_uninterruptible(1); else cond_resched(); -- 2.7.0
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